Segment Information - Segment Profitability and Reconciliation to Net Income (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Adjusted EBITDA									$ 1,196,790	$ 971,510	$ 850,499
Amortization of intangible assets	$ 21,023	$ 14,105	$ 30,396	$ 15,068	$ 14,770	$ 14,333	$ 14,062	$ 13,776	80,592	56,941	49,410
Depreciation and amortization of property, equipment and leasehold improvements	7,929	6,809	7,020	7,143	7,281	7,494	7,463	7,567	28,901	29,805	29,999
Impairment related to sublease of leased property									7,702
Acquisition-related integration and transaction costs									6,870
2016 Multi-Year PSUs grant payroll tax expense											15,389
Operating income	280,587	280,230	257,533	254,375	234,085	227,620	215,175	207,884	1,072,725	884,764	755,701
Other expense (income), net	34,824	79,580	61,838	38,347	38,919	38,577	76,008	45,035	214,589	198,539	152,383
Provision for income taxes	51,898	30,774	30,272	19,209	38,950	6,685	24,044	14,724	132,153	84,403	39,670
Net income	$ 193,865	$ 169,876	$ 165,423	$ 196,819	$ 156,216	$ 182,358	$ 115,123	$ 148,125	725,983	601,822	563,648
Index [Member]
Segment Reporting Information [Line Items]
Adjusted EBITDA									951,312	766,493	670,188
Analytics [Member]
Segment Reporting Information [Line Items]
Adjusted EBITDA									198,799	172,924	152,113
ESG and Climate [Member]
Segment Reporting Information [Line Items]
Adjusted EBITDA									29,748	22,851	21,813
All Other - Private Assets [Member]
Segment Reporting Information [Line Items]
Adjusted EBITDA									$ 16,931	$ 9,242	$ 6,385